Almost from the moment that a pro-Trump mob stormed into the Capitol on Jan. 6, 2021, conspiracy theories have ricocheted from the fringes of the internet to the corridors of Congress. Republican officials and others on the right have dismissed the attack as the work of mere tourists, or sought to depict it as a false-flag operation by shadowy leftist groups — or even the federal government.
These baseless claims have seeped into dozens of criminal cases stemming from the riot, and for more than two years the government has had to beat them back.
On Thursday, prosecutors may face their stiffest challenge yet on that front as Alan Hostetter, a former police chief turned yoga instructor from Southern California, goes on trial in Federal District Court in Washington. Few people connected to the Jan. 6 attack have embraced conspiracy theories about the attack as fully as Mr. Hostetter, who is planning to place them at the heart of his defense.
Acting as his own lawyer, Mr. Hostetter has said that he intends to fight charges of conspiracy and obstruction based on what he calls “three fundamental pillars”: that the 2020 election was stolen from President Donald J. Trump; that he and other rioters had no desire to disrupt the challenges to the vote results that were taking place inside the Capitol on Jan. 6; and that, therefore, the assault on the building had to have been staged by “federal law enforcement and intelligence agencies.”
To prove all this, Mr. Hostetter had initially told the judge who will hear his trial that he wanted to call as many as 30 witnesses as part of his defense.
Among those on his list were former Speaker Nancy Pelosi and her daughter; Jacob Chansley, a fellow rioter better known as the QAnon Shaman; a New York Times reporter who wrote an article about his wife; and the general manager of the Kimpton George Hotel near the Capitol, where Mr. Hostetter stayed on Jan. 6 and which, as one of his motions said, was probably the place that the “feds” used to surveil him.
While Mr. Hostetter eventually backed away from his request, the trial is likely to draw together many of the disparate strands of conspiracy theories that have stubbornly taken root on the right in the two and a half years since the Capitol was attacked.
Prosecutors have warned for weeks that the proceeding could devolve into chaos.
“The defendant’s goal with this trial — rather than a genuine engagement on the elements or the evidence — is to create a circuslike atmosphere and to promote his own brand,” they wrote last month to Royce C. Lamberth, the presiding judge.
The vast majority of the more than 60 Capitol riot cases that have gone to trial in Washington so far have fallen into one of two buckets. They have either been brief and straightforward assault or trespassing matters, or longer and weightier conspiracy cases involving complex charges like sedition against members of extremist groups such as the Proud Boys and the Oath Keepers militia.
Every now and then, the trials have veered from this normal course as defendants have taken the stand to offer unusual — and generally unsuccessful — arguments like blaming Mr. Trump for their decision to storm the Capitol. But while some of the trials have at times been dramatic, most have been relatively uneventful and largely trouble-free.
A leader of a group called the American Phoenix Project, which was founded to fight the “fear-based tyranny” of coronavirus-related restrictions, Mr. Hostetter was accused of plotting with several members of the Three Percenter militia movement to storm the Capitol and stop the certification of Mr. Trump’s defeat.
Shortly after the election, prosecutors said, Mr. Hostetter and another leader of the American Phoenix Project, Russell Taylor, began to use the group “to advocate violence” against people that “supported the 2020 election results.” At the end of November, for example, Mr. Hostetter posted a video on the group’s YouTube channel accusing those who had not challenged the results of committing treason.
“Some people at the highest level,” he said, “need to be made an example of with an execution or three.”
Prosecutors say that Mr. Hostetter and Mr. Taylor communicated with their Three Percenter co-defendants mostly through a group chat on Telegram called “California Patriots-DC Brigade.” Mr. Taylor once described the channel as being for “able bodied individuals that are going to DC on Jan. 6” and are “ready and willing to fight.”
Mr. Hostetter went to Washington on Jan. 3, 2021, prosecutors said, checking into a room at the Kimpton George. Three days later, carrying a hatchet in a backpack, he accompanied Mr. Taylor — who also had a hatchet as well as a knife and a stun baton — into a restricted area on the Capitol grounds.
In April, in a nod to the unusual nature of Mr. Hostetter’s proposed defense, Judge Lamberth severed his case from the four co-defendants who stood accused of being Three Percenters and conspiring to disrupt the certification of the election on Jan. 6. By that time, Mr. Taylor had already pleaded guilty to conspiracy charges and under a deal with the government had agreed to serve as a witness and testify against Mr. Hostetter at trial.
Prosecutors have said that they intend to bolster their case with testimony from F.B.I. agents who conducted the investigation and police officers who witnessed the violence at the Capitol. But this standard presentation could be upended if Mr. Hostetter tries to pursue the more outrageous parts of his defense.
Last month, for instance, during a routine pretrial hearing, he went on a tirade, accusing the government of having prosecuted Stewart Rhodes, the leader of the Oath Keepers, on sedition charges in order to disguise the fact that Mr. Rhodes had been working with the authorities on Jan. 6.
Judge Lamberth cut him short and dismissed his baseless claims.
“You don’t have any facts to support your allegations,” he said.